Flashing
Another major component of the "weather envelope" is flashing. Flashings are the devices used to keep any water stopped by a barrier or collected in a wall under control until it can be redirected and deposited to the outside of the building. One of the most important components of a structure, flashings are the components or materials used to ensure that any water that penetrates the skin of the building and has stopped at the water-resistive barrier is contained, collected, and conducted back to the outside of the skin of the building.
If the purpose of building is to enclose spaces so that they may be used by people for specific purposes, the two major systems providing a means to that end are the structural system and the weather protection system. The structural system actually encloses or creates the space, while the weather protection system maintains the space as "interior," protected from the elements and suitable for many and varied uses. Flashings are to the weather protection system as connections are to the structural system. Without flashings, the weather protection system does not work. The code-mandated water-resistive barrier is ineffective without flashings at all openings, terminations, corners, edges, and wall tops and bottoms.
The importance of flashings, their correct installation, as well as how and why they are integrated with the water-resistive barrier into a complete functioning system seems widely misunderstood and undervalued in the construction industry, and consequently is one of the ultimate causes of many construction defect claims involving water penetration.
